Head injury and the risk of Alzheimer's disease: a case control study.

OBJECTIVES

The objective of this study is to examine the association between Alzheimer's disease and head injury in elderly patients referred to an EMI unit.

METHOD: An unmatched case control study comparing 198 cases of Alzheimer's disease (NINCDS-ADRDA diagnostic criteria) to selected controls (164 other dementias and 176 non-dementing group) with respect to history of head trauma, with or without loss of consciousness, prior to the onset of dementia.

SETTING

EMI unit in Warrington serving an elderly population of 28,000. The subjects included all patients referred to and seen by the first author during a 2-year study period 1991-1993.

MAIN OUTCOME MEASURE: Relative risk (odds ratio) of Alzheimer's disease.

RESULTS

For having history of head injury, the odds ratio was 1.52 (0.98-2.35), significant only in male patients (OR 2.1 p < 0.05). For dementias other than Alzheimer's disease the odds ratio of head injury was 2.36 and 2.46 for all dementias combined (p < 0.05).

CONCLUSION

The study confirms a positive association between reported head injury and Alzheimer's disease as well as non-Alzheimer type dementia. Head trauma did not appear to be a specific risk for Alzheimer's disease as previously claimed. The association was modified by sex being only significant in male patients.